My table of Integrals has the overall scenario ##int frac dx x^2+a^2 ## like a 'normal' integral way too, not simply the case in which ##a=1##. But I do think this remaining a Calculus research challenge it is anticipated on the OP to figure out how to do it. Hints https://gabletoppak.com/how-gable-top-pak-and-paper-bottles-lead-in-sustainable-beverage-packaging/